Drill pipe cleaner plug with valve



J. F. ARNOLD 3,276,520

DRILL PIPE CLEANER PLUG WITH VALVE Flled Feb 20, 1964 INVENTOR Jamas E flrlwzoi MW M ATTORNEYS Oct. 4, 1966 United States Patent 3,276,520 DRILL PIPE CLEANER PLUG WITH VALVE James F. Arnold, 4029 9th St., Marrero, La. 70072 Filed Feb. 26, 1964, Ser. No. 346,1% 4 Claims. (Cl. 166-170) This invention relates to an apparatus for use in avoiding the overflow of drilling mud onto a drilling platform when pipe is withdrawn from an oil well.

During the drilling of an oil well it is periodically necessary to withdraw the pipe in order that the drilling bit at its lower end may be replaced. At such time the well, both inside and outside the pipe, is full of drilling mud which is a fluid introduced into the well at the top of the pipe, circulated through openings in the drill bit to wash away fragments cut from the soil and rock by the bit, and drawn up the well with this material, outside the pipe, in a process generally referred to as circulation. Since the mud outside the pipe contains the cuttings of the bit, together with material washed from the wall of the well, and the mud inside the pipe does not, the fluid outside the pipe is heavier than that inside. Consequently, once the pumping of drilling fluid ceases, and the pressure exerted by the pump on the fluid in the pipe is relieved, this fluid tends to rise within the pipe, to a level above that prevailing within the well outside the pipe. As a result, each section of pipe that is pulled up continues to hold fluid, and when it is disconnected from the remainder of the string, this fluid flows out over the platform, making an undesirable mess, and causing a waste of drilling fluid.

This problem is commonly avoided by pumping into the pipe a heavy fluid, ordinarily a barium compound, which will equalize the specific gravity inside and outside the pipe. This is, however, expensive, since the heavier fluid is in itself expensive and some of it is lost each time it is used. Moreover, it is necessary to maintain a tank with a supply of it on hand at all times.

It has been suggested that a sub with a check valve for preventing reverse circulation may be dropped into the pipe, and attached to the inner wall of the pipe by suitable means carried by the sub, which may be actuated from above. The difliculty is that the sub must let down a long distance in a pipe which is not always straight, and must fit tightly enough to block reverse flow when its valve is closed. Such a sub is very likely to get stuck at some intermediate point, and is diflicult to dislodge when this occurs. Moreover, a very long cable is required for a deep well. This method has consequently not been adopted on any large scale, and, so far as I am aware, it is still the almost universal practice to rely on heavy fluid additives.

It is accordingly the object of my invention to solve this problem completely without waste of additives or risk of jamming a sub in the pipe near the bottom of the well. This is accomplished by dropping into the pipe a heavy weight which completely seals it against the rise of liquid past the Weight and at the same time exerts a pressure on the liquid in the pipe suflicient to balance the force resulting from the greater specific gravity of the fluid outside the pipe.

The preferred apparatus for carrying out my invention will now be described in detail with reference to the accompnaying drawings, in which:

FIG. 1 is a schematic vertical sectional view showing the top of an oil well with one of my plugs inserted in the top of the pipe, ready to be dropped; and

FIG. 2 is an exploded view showing the parts of my plug in alignment, with their right-hand halves in axial section.

Like reference numerals denote like parts in both views.

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Referring now to FIGURE 1, a conventional oil well comprises an outer wall 10, encircling a string of pipe 11. The pipe passes through rotary slips 12 in a rotary table 13 at the rig floor level, and terminates at its upper end in a tool joint 14. Mud is withdrawn from the well through a flow line 15, and it will be observed that the mud 16, outside the pipe, carries the drill chips 17 which make it heavier than the mud 18 inside the pipe.

At the top of the string a conventional dropping plate 19 supports a plug 20 which, as shown in FIG. 2, comprises the following parts, reading from top to bottom:

21-Spearhead for fishing plug out if need be.

ZZfiSlOtted member to receive drop plate.

23Sleeves between which pressure cups are clamped.

24-Resilient pressure cups which seal against the inner wall of the pipe to prevent fluid from rising above the plug.

25Back-up cups for the resilient pressure cups.

26-Externally threaded spigots at bottoms of sleeves, and on which the cups are threaded.

27Internally threaded female spigots at tops of sleeves which are screwed onto male spigots thus gripping the cups between adjacent sleeves.

28Central bore in sleeves for circulation of drilling fluid.

29Passageway in upper sleeve leading to bore.

30Passageway in lower sleeve leading to bore.

31-Seat in lower sleeve for plug valve.

32Plug valve which is pressure fit in seat 31.

33Weight for applying pressure to surface of fluid.

The plug valve will stay in its seat as long as there is no substantial downward pressure exerted against it. If, however, the plug is diflicult to withdraw, any vacuum may be broken by pumping fluid down onto the bore against the top of the plug valve which will then drop into the second seat formed in the enlarged bottom portion of the bore 28 by the top of the weight 33, thus permitting free passage of air or fluid through the bore 28.

The operation of my process is as follows:

The plug is first positioned as shown in FIG. 1. The drop plate 19 is then withdrawn, and the plug 20 falls to the top of the fluid 18. When the cups 24 encounter the surface of the liquid 18, they are forced outwardly to form a liquid tight seal against the wall of the plug. The cups are carefully designed so that they will not act of themselves to form air-tight seal as the plug is being dropped, which would prevent it from reaching the surface of the drilling fluid, but will form a liquid-tight seal when expanded outwardly by the resistance of the drilling fluid, sail seal being capable of resisting the pressure imposed by the weight. The result is that the plug floats on the fluid exerting a downward pressure on it equal to the weight of the plug, which may be made suflicient to offset the dilference between the specific gravity of the fluid inside the pipe and that outside it.

Pipe is then withdrawn, section by section, in the usual manner, each section being unscrewed as it rises above the rig floor. As the pipe is pulled up, the plug remains stationary on the top of the fluid, below the rig floor, so that no overflow occurs. The plug comes up just ahead of the bit.

While I have described one method of carrying out my invention and one plug suitable for use in connection therewith, it will be readily appreciated that both the plug and the method of handling it may be varied as to detail without thereby departing from the essentials of the invention as defined by the following claims.

What is claimed is:

1. A device for applying pressure to the drilling mud in a pipe when drilling oil wells, said device comprising a heavy body, at least one downwardly open expansible cup member encircling and fixed to said body, said cup member being made of a resilient material having a resistance to radial expansion suflicient to prevent its expansion against the inner wall of said pipe sufficiently to form a seal thereagainst when being lowered in said pipe against the resistance of air at atmospheric pressure, but having sufiicient elasticity to expand and form a seal against said inner pipe wall when being lowered into a liquid, said body being formed with an upper port above said cup, a lower port below said cup, and a duct connecting said ports, and valve means controlling the passage of fluid through said duct, said valve means comprising a valve member releasably retained in a first position in which it prevents upward flow through said duct, said valve member being movable, in response to pressure thereon from above said body, to a second position in which it permits flow of fluid through said duct, in either direction, and is no longer retained in said first position, but is biassed into its second position by any fluid flowing in either direction through said duct.

2. A device as claimed in claim 1 in which said valve comprises a seat into which said valve member is force fitted when in said first position, so as to be retained in said first position.

3. A device as claimed in claim 2 in which said valve comprises a second seat into which said valve member fits loosely when in said second position, an orifice encircled by said first seat leading to said duct and blocked by said valve member when in said first position, and an orifice between said seats opening to the exterior of said body member, and serving as said lower port.

4. A device as claimed in claim 1 in which said valve is positioned below said cup.

References Cited by the Examiner UNITED STATES PATENTS 1,527,749 2/1925 Raymond 166153 2,225,413 12/1940 Fester van et a1. 166-170 2,257,080 9/1941 Turner 166170 2,257,784 10/1941 Brown 166-170 2,460,481 2/1949 Abel 15104.05 2,740,480 4/1956 Cox 166170 CHARLES E. OCONNELL, Primary Examiner.

J. A. LEPPINK, Assistant Examiner. 

1. A DEVICE FOR APPLYING PRESSURE TO THE DRILLING MUD IN A PIPE WHEN DRILLING OIL WELLS, SAID DEVICE COMPRISING A HEAVY BODY, AT LEAST ONE DOWNWARDLY OPEN EXPANSIBLE CUP MEMBER HAVING CIRCLING AND FIXED TO SAID BODY, SAID CUP MEMBER BEING MADE OF A RESILIENT MATERIAL HAVING A RESISTANCE TO RADIAL EXPANSION SUFFICIENT TO PREVENT ITS EXPANSION AGAINST THE INNER WALL OF SAID PIPE SUFFICIENTLY TO FORM A SEAL THEREAGAINST WHEN BEING LOWERED IN SAID PIPE AGAINST THE RESISTANCE OF AIR AT ATMOSPHERIC PRESSURE, BUT HAVING SUFFICIENT ELASTICITY TO EXPAND AND FORM A SEAL AGAINST SAID INNER PORT BELOW SAID CUP, AND A DUCT CONNECTING SAID BODY BEING FORMED WITH AN UPPER PORT ABOVE SAID CUP, A LOWER PORT BELOW SAID CUP, AND A DUCT CONNECTING SAID PORTS, AND VALVE MEANS CONTROLLING THE PASSAGE OF FLUID THROUGH SAID DUCT, SAID VALVE MEANS COMPRISING A VALVE MEMBER RELEASABLY RETAINED IN A FIRST POSITION IN WHICH IT PREVENTS UPWARD FLOW THROUGH SAID DUCT, SAID VALVE MEMBER BEING MOVABLE, IN RESPONSE TO PRESSURE THEREON FROM ABOVE SAID BODY, TO A SECOND POSITION IN WHICH IT PERMITS FLOW OF FLUID THROUGH SAID DUCT, IN EITHER DIRECTION, AND IS NO LONGER RETAINED IN SAID FIRST POSITION, BUT IS BIASSED INTO ITS SECOND POSITION BY ANY FLUID FLOWING IN EITHER DIRECTION THROUGH SAID DUCT. 